package bishi.day33_6_1;

import java.util.*;

/**
 * 斐波那契额数变型
 *
 * @author 是阿秋啊
 * @date 2022/06/01 13:01
 **/
public class ke_si_yun_lai {
    static long[] arr = new long[81];
    static {
        arr[1] = arr[2] = 1;
        for (int i = 3; i < 81; i++) {
            arr[i] = arr[i - 1] + arr[i - 2];
        }
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            int start = sc.nextInt();
            int end = sc.nextInt();
            long sum = 0;
            for (int i = start; i <= end; i++) {
                sum += arr[i];
            }
            System.out.println(sum);
        }
    }
}
